Plastic bag or the like with handle

ABSTRACT

A method of manufacture of plastic bags with handles formed from a tube of thin film plastic material and with the handles formed from the same material as the bag walls. Portions of the sidewalls of the tube of plastic material are cut away to form the handles, and in order to provide handles of sufficient strength to carry the load and to properly distribute the resulting stresses over the entire sidewalls of the bag, the tubular thin film of plastic is extruded so as to have portions thereof formed of a thicker material than the rest of the bag walls, and the handles are located so as to include portions of the thicker material.

United States Patent Inventors Heikki S. Suominen;

Vilio J. Makinen; Aarno S. Lindstrom, all of Tampere, Finland Appl. No.823,322

Filed May 9, 1969 Division of Ser. No. 699,988, Jan. 8, 1968, Pat. No.3,482,761.

Patented Sept. 21, 1971 Assignee said Suominen, by said Makinen andLindstrom PLASTIC BAG OR THE LIKE WITH HANDLE 1 Claim, 2 Drawlng Figs.

Int. Cl B3lf l/00 Field of Search 156/244,

Primary Examiner-Samuel W. Engle Att0rney-Hall, Pollock & Vande SandeABSTRACT: A method of manufacture of plastic bags with handles formedfrom a tube of thin film plastic material and with the handles formedfrom the same material as the bag walls. Portions of the sidewalls ofthe tube of plastic material are cut away to form the handles, and inorder to provide handles of sufficient strength to carry the load and toproperly distribute the resulting stresses over the entire sidewalls ofthe bag, the tubular thin film of plastic is extruded so as to haveportions thereof formed of a thicker material than the rest of the bagwalls, and the handles are located so as to include portions of thethicker material.

This application is a division of our copending application 5 Ser. No.699,988, now U.S. Pat. No. 3,482,761, filed Jan. 8, 1968.

BACKGROUND OF THE INVENTION It is well known in the art to provideplastic bags which are formed from a continuous tube or extruded plasticmaterial. Successive bags are cut from the tubular material with thelength of the bag lying along the axis of the tube. The bottom of eachcutout portion is heat sealed to form the closed bottom of the bag, andadditional portions of the tube are cut away at the other or top end ofthe bag to form spaced carrying handles which are heat-sealed at theirtopmost edges to form continuous carrying loops extending between thefront and rear bag walls.

It is also old in the art to provide bags of this general type in whichthe carrying means for the bag does not comprise space loops but insteadis formed of registering hand holes or apertures cut out of the frontand back walls and with the mouth of the bag open. With both types ofthe aforesaid constructions, one of the problems which arises is thatwhen an appreciable load is carried in the bags, there is a highconcentration of forces adjacent to the handle or carrying means. Thus,where the spaced loops are provided by cutouts at the top of the bag,there is a high concentration of tensile forces along the loop formingthe handle and also at the point of juncture of each handle or loop withthe front and rear bag walls. Similarly, with they type of constructionusing the registering apertures in the front and back bag walls, thereis a high concentration of forces in the material of the front and backwalls immediately adjacent the aperture. One way to overcome thisproblem is to construct the bag of sufiiciently thick therrnoplasticfilm to ensure that the resultant forces can readily be borne withoutrupturing the material of which the bag is formed for the expected sizeof load carried in the bag. This, however, results in a product which isnot commercially competitive because of the excessive amount of materialused in the manufacture of each bag. Another solution which has beendevised is to laminate extra strips or bands of thermoplastic materialto the bags and/or to the handles of the bag in such a manner that theforces resulting from the carrying of a heavy load in the bag aredistributed along the thus reinforced portions. This attempted solutionis also not entirely satisfactory because of the difficulties inherentin the lamination process which not only involves extra material costsbut also reduces the speed of manufacture.

It is proposed, according to the present invention, to overcome theaforesaid difiiculties in bag manufacture by extruding the thermoplastictube of material with thickened walls over selected portions thereof insuch manner that the thickened portions are so disposed as to absorb thestresses resulting from the carrying of a heavy load in the bag. In theillustrated embodiment, which is particularly concerned with a type ofbag construction providing for two spaced carrying handles formed bysuitable cutouts formed at the top of the bag, thickened extrudedportions are provided about the periphery of the tube at four differentlocations so that, in the resulting bags, there will be two spacedreinforced portions on both the front and rear bag walls with each pairon one of the bag walls being spaced so as to be longitudinally alignedwith the carrying handles or straps.

Referring to the drawings:

FIG. 1 illustrates the manner of construction of a bag of the presentinvention from a continuous tube of extruded thermoplastic material; and

FIG. 2 is a cross-sectional illustration of the extruded tube from whichthe bag of the present invention is made, particularly illustrating thethickened extruded portions.

The bag of the present invention is made from a tubular sheath 1 of athermoplastic, heat-sealable film. As shown in FIG. 1, crosswise seams 3are formed in the tubular material at spaced intervals corresponding tothe desired longitudinal length of each bag. Such crosswise seams may beformed by heat welding together in a known manner the front and rearwalls of the tubular sheath 1. Spaced portions 5, 6, and 7 are cut outof the tubular seam as shown in FIG. 1, and the portions cut out extendupwardly into the crosswise sheath 3 so that the subsequent cuttingoperation through the seams 3 at 9, Le, along the midpoint of the seam3, will intersect the cutout portions 5, 6, and 7 and thereby leave anopen mouth for the bag other than for the carrying straps 8. It will benoted that the front and rear carrying straps of each pair are joinedtogether at the top by the crosswise seam 3.

It can be appreciated that a bag formed with spaced carrying handles inthe manner illustrated in FIG. 1 will, when heavily loaded, produce ahigh degree of stress of the thin film material along those portions ofthe front and rear side walls which are longitudinally aligned with thecarrying straps or handles 8 and that this will tend to rupture thematerial. For this reason, the bag of this invention is provided withreinforced portions 2 comprising longitudinally extending webs ofthickened material which are formed in the extrusion of the materialfrom the extruder die. In FIG. 2, the thickened portions are shown ascomprising relatively narrow bands, but it will be apparent to oneskilled in the art that the thickened extruded portions can be muchwider than shown in FIGS. 1 and 2 and may, if desired, extend at leastas wide as the width of each of the carrying straps 8.

It will also be apparent to one skilled in the art that a singlethickened extruded band may be provided on both sides of the tubularsheath, but extending generally down the midsection thereof. In such anembodiment (not shown) the handles for the bags may be formed bypunching out a finger grip lying in the thickened extruded portion sothat the stresses of carrying the loaded bag are borne by the thickerweighted material running along the center of the front and rear bagwalls.

It is, of course, also within the scope of the invention to make thereinforced or thickened zones of extruded material of a different colorthan the rest of the material of the bags by extruding the thickenedzones from different nozzles. Also, instead of providing merely onethickened longitudinal zone in each of the handles 8, it is, of course,possible to provide two or more such thickened portions in each handlemember 8.

What I claim is:

l. A method for making a thermoplastic bag having at least oneintegrally formed handle comprising the steps of extruding tubularsheath of thermoplastic film having four laterally spaced longitudinallyextending band portions thereof which are of greater film thickness thanthe remainder of said sheath so as to form a plurality of reinforcingzones,

flattening said sheath to form a flattened tube having front and rearpanels and with said band portions of greater thickness overlying eachother in pairs with each pair of said thicker band portions lyinginwardly the same predetermined amount from the side edges of theflattened sheath,

heat-sealing together said front and rear panels at spaced intervalssubstantially corresponding to the length of each bag to from transverseseams,

cutting out three portions of the juxtaposed front and rear wallsadjacent one of said transverse seams in each space between a pair ofsaid seams to form two bag handles for each bag adjacent the top of saidbag,

a first of said cutout portions lying between said two pairs ofreinforcing zones and the other two said cutout portions each extendinginwardly from a respective edge of the sheath to a point short of therespective longitudinally extending reinforcing zone to thereby form twospaced handle loops each of which is longitudinally aligned with one ofsaid reinforcing zones,

and cutting said flattened tube along each transverse seam to separateeach bag from the next.

